Electrical switch



Jan. 13, 1948. o. FROLAND ELECTRICAL SWITCH Filed Dec. 17, 1943 2Sheets-Sheet 1 R a A J 3 2 2b 2 Z 7 w n a a w\/\\o v w I I i 7 0 o 3 57M n 5 a 7 7 J i 0 62 ,2 l5 ,6 66 I 68 56 J5 Z6 65 70 56 7 s7 24 5 3 Z4/ I a 65 f z I Jan. 13, 1948. o. FROLAND 2,434,315

ELECTRICAL SWITCH Filed Dec. 17, 1943 2 Sheets-Sheet 2 41' TORI/E M OuwFRouu/q Patented Jan. 13, 1948 ELECTRICAL SWITCH Olav Froland, St.Louis, Mo., asslgnor to James R. Kearney Corporation, St. Louis, Mo., acorporation of Missouri Application December 17, 1943, Serial No.514,629

Claims.

This invention relates generally to electrical switches, and morespecifically to electrical switches of the type comprising movablysupported switch blades movable into and out of electrical contact withcontact means so as to complete or interrupt electrical circuits inwhich the switches are interposed, the predominant object of theinvention being to provide such an electrical switch with improved,rapidly operating means for quickly interrupting or breaking the circuitat a point remote from the contacts of the switch, with which the switchblade makes electrical contact, so as to protect said contacts, and theswitch blade from the injurious effects resulting from arcing when theswitch blade is drawn from the closed-switch position to the open-switchposition.

Fig. 1 is a side elevation of an electrical switch equipped with theimproved quick-break means of the present invention.

Fi 2 is a front elevation of the switch assembly illustrated in Fig. 1.

Fig. 3 is an elevation of the switch assembly illustrated in Figs. 1 and2 when Viewed from the side opposite to that illustrated in Fig. 1.

Fig. 4 is an enlarged, fragmentary horizontal section taken on line 44of Fig. 1.

Fig. 5 is a longitudinal section taken on line 55 of Fig. 4.

Fig. 6 is an enlarged, vertical section of a portion of the improvedquick-break mechanism of the present invention.

Fig. 7 is an enlarged, cross-section taken on line 'I--'l of Fig. 5.

Fig. 8 is an enlarged, cross-section taken on line 88 of Fig. 5.

Fig. 9 is an enlarged, horizontal section taken on line 99 of Fig. 5.

Fig. 10 is a view similar to Fig. 5, but showing the switch blade andparts of the quick-break mechanism in positions different from thepositions occupied by said parts in said Fig. 5.

Fig. 11 is a vertical section taken on the staggered line ll-Il of Fig.10. s

Fig. 12 is a view partly in elevation and partly in section of a part ofthe quick-break mechanism of the present invention.

In the drawings, wherein is shown for purposes of illustration, merely,one embodiment of the invention, A designates generally the switchillustrated in Figs. 1, 2 and 3. The switch A comprises a suitablesupporting member l on which are mounted a pair of insulators 2 and 3.The insulator 2 has fixed thereto a terminal member 4 which is providedwith an upwardly projected extension 4' to which an incoming electricalconductor Ca is suitably connected, mechanically and electrically. Also,the insulator 3 has fixed thereto a terminal member 5 having adownwardly projected extension 5' to which an outgoing electricalconductor Cb is mechanically and electrically connected by suitablemeans. The terminal member 4 supports a contact structure 6 and theterminal member 5 supports a similar contact structure I, said contactstructures 6 and I being each made up of a plurality of resilient rod orwire elements shaped in plan as is shown in Fig. 4.

The terminal member 5 is provided with spaced, forwardly projectedextensions 8 which support a switch blade 9 for pivotal movement intoand out of electrical contact with the contact structures 6 and I, saidswitch blade having clamped thereto a member Ill that has trunnions IIassociated therewith which are rotatably received .in openings formed inthe extensions 8 of the terminal member 5. The terminal member 4, at theupper end of the switch A, is provided with extension means l2 to whichis pivotally attached a switch blade latch I3 that is provided with abifurcated outer portion having spaced legs shaped to engage projectedelements l3 carried by the switch blade 9 so as to lock the switch bladein its closed-switch position. Also, the switch blade 9 has pivotedthereto a latch operating member M which is provided with spaced camportions N that engage and elevate the outer portion of the latch [3,when the outer eye portion of the latch operating member I4 is moveddownwardly, to disengage said latch from the elements l3 of the switchblade, so as to permit outward pivotal movement of the switch blade fromthe closed-switch position to the openswitch position.

Supported by the insulator 2 of the switch A is a quick-break mechanismwhich is designated generally by the reference character Q. saidquick-break mechanism including a member l5 from which an integral armI6 is extended. the member I5 and the arm l6 being formed of electricalconducting material and said arm is suitably secured to said insulator 2in electrical contact with the terminal 4 (Fig. 4). The member i5supports a tubular element ll formed of suitable electrical insulatingmaterial, said member l5 being of annular, cup-shaped formation and anend portion of the tubular element I1 is seated in said member with abody of cement l8, or other suitable material (Fig. 6), being providedto rigidly secure said tubular element to said member I5, At the end ofthe tubular element opposite to the end thereof at which the member I5is located, said tubular element has secured thereto a housing I9 whichis formed of electrical conducting material, this housing having anannular cup-shaped portion 20 into which the forward end portion of thetubular element H is extended, and a body of cement 2|, or othersuitable material, being provided to rigidly secure said housing I9 tosaid tubular element IT. The housing I9 is of the shape illustrated togood advantage in Figs. 4, 5, and 11; that is to say, said housing isprovided with a top wall, opposed side walls, and a bottom wall having adownwardly projected extension l9, said housing l9 having an opening 22formed in a side wall thereof and this opening is closed by a plate 23(Fig. 11) which is suitably secured in place. Also, the housing I9 isprovided with a rear wall 24, that forms a part of the cup-shapedportion 20, and through which rear wall a centrally located opening isformed. Likewise, the housing includes a forward end wall which isprovided with a centrally located opening that is covered by a plate 25.

Secured to the member |5 of the quick-break mechanism Q is an element 26(Fig. 6) which is formed of electrical conducting material and comprisesan annular portion provided with an outstanding, annular flange 26'having apertures through which fastening devices pass for securing saidelement 26 to the member IS. The element 26 supports a rearwardlyextended tubular structure 2! which is closed at its rear end by aclosure element 28, the forward end portion of said tubular structureembracing the annular portion of the element 26 and fastening devices 29being employed for rigidly securing said tubular structure to saidelement 26. The tubular structure 21 comprises an outer tube formed ofinsulating material which possesses sufficient mechanical strength andgood weather-resisting qualities, and an inner lining tube whichpreferably is formed of horn fiber, or other suitable material, which ischaracterized by the ability to give off gas in the presence of the heatof an electrical arc which tends to extinguish the arc. The tubularstructure 21 is provided at its bottom with an elongated slot 30 whichextends longitudinally of said tubular structure and provides for theescape of gas from the chamber within said tubular structure duringoperation of the quick-break mechanism.

Screwthreadedly connected to the element 26, as shown to good advantagein Fig. 6, is a tubular, coupling member 3|, said coupling member havingan internally screwthreaded end portion which is screwed into ascrewthreaded opening 32 of said element 26. At its opposite end thecoupling member 3| is internally screwthreaded and screwed into saidinternally screwthreaded end portion of said coupling member 3| is-atubular structure 33. The tubular structure 33 comprises an outer tube34 which is formed of electrical insulating material possessing therequired mechanical strength, and an inner tube 35 formed of horn fiber,or other material, characterized by the ab lity to give off gas in thepresence of the heat of an electrical are which tends to extinguish thearc. The tubular structure 33 which extends through the tubular elementl1, abuts at one end with an inwardly projected, annular head 36 formedwithin the coupling member 3|, and at the opposite end of said tubularstructure 33 the tube 34 abuts against the rear face of the wall 24 ofthe cup-shaped portion 20 of the hous ing is, the extreme forward endportion of the inner tube 35 being seated in the centrally locatedopening formed through said wall 24.

Arranged within the housing l9 and extended longitudinally thereof, is apair of spaced, substantially parallel rods 31, the opposite ends ofsaid rods being supported, respectively, by the wall 24 and the forwardwall of the housing l9 by being provided with end portions which areseated in apertures in said walls of the housing. The spaced rods 31support for guided, straight-line, sliding movement with respect theretoa head 38 from which is extended in a rearward direction a rod 39 formedof electrical conducting material, said rod 39 being provided with aforward portion 39' of reduced diameter which is extended into anopening formed in the head 38 and is secured therein by a pin 40 (Fig.12). At its opposite end the rod 39 has fixed thereto a follower 4|which preferably is formed of horn fiber or other suitable electricalinsulating material, that is so characterized as to give off gas in thepresence of the heat of an electric are which tends to extinguish thearc. The follower 4| preferably is of substantially the same diameter asthe rod 39, and it is secured to the rod by having a reduced end portion42 of the rod forced into an opening formed in an end portion of thefollower (Fig. 6).

By referring particularly to Fig. 6 of the drawings, it will be notedthat the tubular element 26 has fixed thereto a contact 43 whichincludes an annular flange portion 44 that is secured to the tubularelement 26, at the rear face thereof, by fastening devices 45. Extendingforwardly from the flange portion 44, and projected through the centralopening of the element 26 is a tubular contact portion 46 which isprovided with circumferentially spaced and longitudinally extended slitsthat extend from the forward edge of the tubular contact portion 46 to apoint spaced rearwardly of said forward edge. These slits provide thetubular contact portion 46 with a plurality of resilient contact fingers41 that are provided with inwardly curved and outwardly flared portionswhich contact, during different phases of the operation of thequick-break mechanism, with the rod 39 and with the follower 4|.

Supported within the lower portion of the downwardly extended portion l9of the housing |9 is a rod 48 which provides pivotal support for a leverstructure 49, said lever structure comprising a hub portion 49a fromwhich is extended a pair of spaced arms 49b. At their upper ends thearms 49b have pivoted thereto a pair of links 50, said links beingdisposed at opposite sides of the head 36 and the ends of the links,opposite to the ends thereof which are pivoted to the arms 49b, beingpivotally connected to said head 38. The arms 49b of the lever structure49 have extended from one to the other thereof an integral portion 5|,an extensible and contractile coil spring 52 being attached at one ofits ends to said lever portion 5| and at its opposite end to the forwardwall of the housing IS. The coil spring 52 tends to move the lever andlink assembly 49- 50, and the head 38, to the positions that such partsoccupy in Fig. 10.

Supported for rotary movement by bearing portions 53 (Fig. 11) formed onthe opposed side walls of the housing |9 of the quick-break mechanism Qis a shaft 54 which extends transversely of said upper portion of saidhousing and extends outwardly beyond the housing. The portion of theshaft 54 which is located within the housing I! has fixedly mountedthereon a toggle link 55,

said toggle link being provided with a hub portion 55' that embracessaid portion of the shaft 54 and is pinned or otherwise secured thereto.At its opposite end the toggle link is bifurcated so as to pivotallyreceive an end portion of an associated toggle link 58, the opposite endof said associated toggle link 56 being pivotally attached to the leverstructure 49 at the location of the portion thereof. The toggle link 55is provided with an extension 55' (Figs. '5 and which serves as anabutment element that contacts with the lower face of the top wall ofthe housing-l9 so as to arrest rotary movement of said toggle link 55 inone direction. Mounted on the shaft 54, at the outer end thereof, is anactuating member 51, which is shaped as is shown to the best advantagein Fig. 3, said actuating member having a cam face 51'51a which servesan important function that will be hereinafterv referred to in detail.The actuating member is preferably formed of electrical insulatingmaterial and it includes a hub portion 58 (Figs. 4 and 11) that embracesthe shaft 54 and is suitably secured thereto.

Secured to the switch blade 9 of the switch A is an arm 59 that isprovided with a clamping portion 69 (Fig. 9) which embraces the switchblade and is clampingly secured thereto by a bolt iii. The opposite endof the arm 59 is provided with a portion 62 through which an opening 62is formed, said opening extending, also, through a portion of anextension 63 that is formed on said arm portion 62. Fixedly disposed inthe opening 52 of the arm portion 62 and the extension 63 is the lowerportion of a rod 64, said rod being extended upwardly from said arm 59in substantial parallelism with respect to the switch blade 9 and beingprovided with anupper, bifurcated portion 55 that rotatably-supports aroller 65 (Fig. 10). Also, the extension 63 of the arm 59 has securedthereto, by means of the fastening devices 61, an auxiliary switch blade88, which is arranged as is shown in Fig. 10. During operation of theswitch blade 9. of the switchA, into and out of the closed switchp0sition,-the auxiliary switch blade 68 movesinto and out of electricalcontact with anauxiliary contact structure 69 (Fig. 4). This auxiliarycontact structure 69 comprises a pair of elongated strips of resilient,electrical conducting material, which are spaced apart slightly and "aresecured to electrical conducting extensions I9 that are projectedoutwardly from an adjacent side wall of the housing IS. The elongatedstrips which produce the auxiliary contact 69 are flaredat their forwardends, as is shown in Fig.- 4, so that the auxiliary switch blade 68 maypass freely between said elongated strips when the switch blade 9 ismoved to the closed-switch position.

In describing the operation of theswitch disclosed herein, it will beassumed that the switch is in the closed-switch position, as is showninFigs. 1, 2, 3, 4, and 5, and that it is desired to operate the switch tothe open-switch position. When the switch is in the closed-switchposition the Switchblade 9 is, of course, in contact with the uppercontact structure '6, and also, the auxiliary switch blade 68 is incontact with'the aux iliary contact structure 99, a portionfof saidauxiliary switch "blade being interposed between the elongated strips ofsaid auxiliary contact. There fore, when the switch is intheclosed-switch position the electrical path through the switch is fromthe conductor Ca, through the upper terminal member 4 and the contactstructure 6 associated therewith, through the switch blade 9 to 6. thelower contact structure I and the, lower terminal member 5 with whichsaid lowercontact structure is associated, and from the switch by way ofthe conductor Cb.

To move the switch blade 9 to the open-switch position the eye portionof the latch operating member I4 is engaged by a switch stick, and saideye portion is drawn downwardly so as to cause the forward portion ofthe latch l3 to be elevated out of engagement'with respect to theelements H" of the switch blade 9, whereupon the upper portion of saidswitch blade 9 is drawn outwardlyand downwardly out of electricalengagement with respect to the contactstructure 6. As the upperportionof the switch blade 9 moves out of contact with respect to theupper contact structure 6, electrical contact between said switch bladeand said contact structure is broken, but no arcing occurs at said uppercontact structure because the auxiliary switch blade 88 is still inelectrical contact with the auxiliary contact structure 69. Therefore,when electrical contact between the'switch blade 9 and the contactstructure 6 has been broken, as described above, the electrical paththrough the switch will be from the conductor Ca, throughthe upperterminal member 4, through the arm l6 of the quickbreak mechanism Q tothe member 15, element 26, and contact 43 (see Fig. 6). The contact 43makes electrical contact with the movable conducting rod 39 of thequick-break mechanism, and therefore electrical energy will flow fromsaid contact 43 through said rod 39 to the traveling head 38. The head38 has electrically connected to itat I0 an end portion of a length offlexible cable 'H which is loosely attached to one of the links 59 andto one of the arms 49b of the lever structure 49 by means of suitableclips 12, the opposite end portion of said length of cable beingelectrically connected to a wall of the housing I9 of the quick-breakmechanism at the point designated by the reference character 13. Fromthe housing l9 the path of the electrical energy is through theauxiliary contact structure 59, through the auxiliary blade 68, throughthe arm 59 and the switch'blade 9 tothelower terminal member 5 and theconductor Cb.

When the electrical path through-the switch is constituted as justdescribed, the movable unit 50- made up of the head 38, rod 39, andfollower M,

is positioned as shown to good advantage in Figs. 4 and 5, at which timethe coil spring 52 tends to move said unit forwardly to the position inwhich it is shownin Fig. 10. However, the coil spring 52 is preventedfrom so moving the unit referred to because of the fact that the pivot56 of the toggle produced by the toggle links 55 and 58 is over deadcenter with respect to the center of the shaft54 and the center of thepivot element which pivotally connects the toggle link 56 to the leverstructure 49. As a result of this sit-'- uation the lever structure 49is locked against pivotal movement in response to pull exerted by thecoil spring 52 and the unit made up of the head 38, the rod 39, and thefollower 4| is locked in the position inawhich said unit is shown inFigsAandS. a

Now, as the switch blade 9 continues to move outwardly and downwardly atits upper end'with respect to the contact structure 6, the roller 66,carried by-the rod 64 fixed to said switch blade 9, moves in contactwith the cam face 51 of the actuating member 51, and when said rollerengages the portion 5'la of said cam face the actuating member 51 willbe rotated because-of such moving engagement of the roller with respectto said cam face portion. The actuating member I! is fixed to the shaft54 as is the toggle link II, and therefore rotation of said shaft I4,because of the rotation of the actuating member 51, will break thetoggle provided by the toggle links 55 and it forwardly and downwardly.The coil spring I! will then move the unit comprised of the head 8|, therod 39, and the follower ll, rapidly in a forward direction to move theconducting rod 39 out of contact with the contact 48, thus breaking theelectrical path through the switch and permitting continued forwardmovement of the outer portion of the switch blade 8 to draw theauxiliary switch blade I! out of contact with respect to the auxiliarycontact structure 69 without arcing. It is to be noted that when theconducting rod 39 of the quick-break mechanism Q moves forwardly inresponse to pull exerted by the coil spring 82, as described above, anyare formed because of the breaking of electrical connection between saidconducting rod 3! and the contact 43 will be stretched or elongated asthe conducting rod moves forwardly. Also, because the follower ll movesforwardly with the conducting rod 39 such elongated arc will be largelyconfined between the outer surface of the follower 4i and the inner faceof the inner tube which surrounds the follower when it has movedforwardly. The follower 4| and the tube are formed of horn fiber, orother suitable material which gives of! gas in the presence of anelectrical are that tends to extinguish the arc, and hence the arc willbe extinguished, the gas so produced escaping through the slot 30 of thetubular structure ll.

When the switch blade 9 is moved from the open-switch position to theclosed-switch position the operation just described is reversed. Inother words, the inward movement of the switch blade 8 causes theauxiliary switch blade II to move into contact engagement with theauxiliary contact structure 58 between the elongated strips thereof.Also, the roller 86 carried by the switch blade 9 will engage the camface 51' of the actuating member 51, which actuating member is at thattime positioned as shown in Fig. 10, to rotate said actuating member andthe shaft 54, on which it is fixedly mounted, so as to move the leverstructure 49 rearwardly by force applied through the toggle links 55 and56. Such movement of the lever structure 49 moves the unit made up ofthe head 38, the conducting rod 39, and the follower rearwardly to theposition in which said unit is shown in Figs. 4 and 5, the pivot 58' ofthe toggle provided by the toggle links 55 and 50 being moved beyonddead center to lock said toggle and maintain the unit referred to in itsrearward position where it is ready for another switch openingoperation, and the upper portion of the switch blade 9 is moved intolocked contact engagement with the contact structure 8.

I claim:

1. An electrical switch comprising a contact structure, a switch bladesupported for movement into and out of contact engagement with respectto said contact structure, a quick-break mechanism comprising a contactmember, a movably supported conducting element in the form of a rodarranged for movement into and out of electrical contact with respect tosaid contact member, spring means which tends to move said movableconducting element out of contact engagement with respect to saidcontact member, toggle means for moving said movable conducting 8element into contact engagement with said contact member, said togglemeans being movable to such position that the elements thereof becauseof their relative positions lock said movable conducting element incontact engagement with respect to said contact member, a single meansactuated by movement of said switch blade out of the closed-switchposition for releasing said movable conducting element for movement outof contact engagement with respect to said contact member, and actuatedby movement of said switch blade into the closed-switch position formoving said movable conducting element into contact engagement with saidcontact member, said single means comprising a pivotally supportedactuating member operatively related to said toggle means and having anelongated cam face, and means carried by said switch blade which engagesa part of said cam face of said pivotally supported actuating member onswitch-opening movement of said switch blade for releasing said movableconducting element for movement out of contact engagement with respectto said contact member, and which engages another part of said cam faceof said pivotally supported actuating member on switch-closing movementof said switch blade for moving said movable conducting element intocontact engagement with said contact member.

2. An electrical switch comprising a contact structure, a switch bladesupported for movement into and out of contact engagement with respectto said contact structure, a quick-break mechanism comprising a contactmember, a movably supported conducting element in the form of a rodarranged for movement into and out of electrical contact with respect tosaid contact member, spring means which tends to move said movableconducting element out of contact engagement with respect to saidcontact member, toggle means for moving said movable conducting elementinto contact engagement with said contact member, said toggle meansbeing movable to such position that the elements thereof because oftheir relative positions lock said movable conducting element in contactengagement with respect to said contact member, a single means actuatedby movement of said switch blade out of the closed-switch position forreleasing said movable conducting element for movement out of contactengagement with respect to said contact member, and actuated by movementof said switch blade into the closed-switch position for moving saidmovable conducting element into contact engagement with said contactmember, said single means comprising a pivotally supported actuatingmember of angular formation operatively related to said toggle means andhaving an elongated cam face, and means carried by said switch bladewhich engages a part of said cam face of said pivotally supportedactuating member on switch-opening movement of said switch blade forreleasing said movable conducting element for movement out of contactengagement with respect to said contact member, and which engagesanother part of said cam face of said pivotally supported actuatingmember on switch-closing movement of said switch blade for moving saidmovable conducting element into contact engagement with said contactmember.

3. An electrical switch comprising a contact structure, a switch bladesupported for movement into and out of contact engagement with respectto said contact structure, a quick-break mechanism comprising a contactmember, a movably supported conducting element in the form of a rodarranged for movement into and out of electrical contact with respect tosaid contact member, spring means which tends to move said movableconducting element out of contact engagement with respect to saidcontact member, toggle means for moving said movable conducting elementinto contact engagement with said contact member, said toggle meansbeing movable to such position that the elements thereof because oftheir relative positions lock said movable conducting element in contactengagement with respect to said contact member. a single means actuatedby movement of said switch blade out of the closed-switch position forreleasing said movable conducting element for movement out of contactengagement with respect to said contact member, and actuated by movementof said switch blade into the closedswitch position for moving saidmovable conducting element into contact engagement with said contactmember, said single means comprising a pivotally supported actuatingmember of angular formation operatively related to said toggle means andhaving an elongated cam face having angularly related cam face parts,and means carried by said switch blade which engages a part of said camface of said pivotally supported actuating member on switch-openingmovement of said switch blade for releasing said movable conductingelement for movement out of contact engagement with respect to saidcontact member, and which engages another part of said cam face of saidpivotally supported actuating member on switch-closing movement of saidswitch blade for moving said movable conducting element into contactengagement with said contact member.

4. An electrical switch comprising a contact structure, a switch bladesupported for movement into and out of contact engagement with respectto said contact structure, a quick-break mechanism comprising a contactmember, a movably supported conducting element in the form of a rodarranged for movement into and out of electrical contact with respect tosaid contact member, spring means which tends to move said movableconducting element out of contact engagement with respect to saidcontact member, toggl means for moving aid movable conducting elementinto contact engagement with said contact member, said toggle meansbeing movable to such position that the elements thereof because oftheir relative positions lock said movable conducting lement in contactengagement with respect to said contact member, a single means actuatedby movement of said switch blade out of the closed-switch position forreleasing said movable conducting element for movement out of contactengagement with respect to said contact member, and actuated by movementof said switch blade into the closedswitch position for moving saidmovable conducting element into contact engagement with said contactmember, said single means comprising a pivotally supported actuatingmember of angular formation operatively related to said toggle means andhaving an elongated cam face having angularly related cam face parts,and means carried by said switch blade including a rotatable elementwhich engages a part of said cam face of said pivotally supportedactuating members on switch-opening movement of said switch blade forreleasing said movable conducting element for movement out of contactengagement with respect to said contact member, and whiih engagesanother part of said cam face of said pivotally supported actuatingmember on switchclosing movement of said switch blade for moving saidmovable conducting element into contact engagement with said contactmember.

5. An electrical switch comprising a contact structure, a switch bladesupported for movement into and out of contact engagement with respectto said contact structure, a quick-break mechanism comprising a contactmember, a movably supported conducting element in the form of a rodarranged for movement into and out of electrical contact with respect tosaid contact member, spring means which tends to move said movableconducting element out of contact engagement with respect to aid contactmember, toggle means for moving said movable conducting element intocontact engagement with said contact member, said toggle means beingmovable to such position that the elements thereof because of theirrelative positions 1001: said movable conducting element in contactengagement with respect to said contact member, a single means actuatedby movement of said switch blade out of the closed-switch position forreleasing said movable conducting element for movement out of contactengagement with respect to said contact member, and actuated by movementof said switch blade into the closedswitch position for moving saidmovable conducting element into contact engagement with said contactmember, said single means comprising a pivotally supported actuatingmember of angular formation operatively related to said toggle means andhaving an elongated cam face having angularly related cam face parts,and means carried by said switch blade including a roller which engagesa part of said cam face of said pivotally supported actuating member onswitch-opening movement of said switch blade for releasing said movableconducting element for movement out of contact engagement with respectto said contact member, and which engages another part of said cam faceof said pivotally supported actuating member on switch-closing movementof said switch blade for moving said movable conducting lement intocontact engagement with said contact member.

OLAV FROLAND.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,286,131 Wallace et al. June9,1942 2,344,113 Schultz Mar. 14, 1944 2,272,717 Ludwig et al. Feb. 10,1942 ,308,026 Rawlins Jan. 12, 1943 2,323,241 Richardson et al. June 29,1943 773,467 Bradshaw Oct. 25, 1904 2,351,826 Lindell et al June 20,1944 982,100 Smith Jan. 17, 1911 FOREIGN PATENTS Number Country Date681,438 Germany Sept. 22. 1939

